Oxidation Of Sulfur Dioxide Research Articles

HOSO2 Released from Mineral Dust: A Novel Channel of Heterogeneous Oxidation of Sulfur Dioxide during Dust Storms

HOSO₂ Released from Mineral Dust: A Novel Channel of Heterogeneous Oxidation of Sulfur Dioxide during Dust Storms

Multiphase Buffering by Ammonia Sustains Sulfate Production in Atmospheric Aerosols

AbstractMultiphase oxidation of sulfur dioxide (SO2) is an important source of sulfate in the atmosphere. There are, however, concerns that protons produced during SO2 oxidation may cause rapid acidification of aerosol water and thereby quickly shut down the fast reactions favored at high pH. Here, we show that the sustainability of sulfate production is controlled by the competing effects of multiphase buffering and acidification, which can be well described by a characteristic buffering time, τbuff. Both GEOS‐Chem simulations and observations show that globally, τbuff is long enough (days) to sustain sulfate production over most populated regions, where the acidification of aerosol water is counteracted by the strong buffering effect of NH4+/NH3. Our results highlight the importance of anthropogenic ammonia emissions and pervasive human influences in shaping the chemical environment of the atmosphere.

Evaporation-Induced Transformations in Volatile Chemical Product-Derived Secondary Organic Aerosols: Browning Effects and Alterations in Oxidative Reactivity.

Volatile chemical products (VCPs) are increasingly recognized as significant sources of volatile organic compounds (VOCs) in urban atmospheres, potentially serving as key precursors for secondary organic aerosol (SOA) formation. This study investigates the formation and physicochemical transformations of VCP-derived SOA, produced through ozonolysis of VOCs evaporated from a representative room deodorant air freshener, focusing on the effects of aerosol evaporation on its molecular composition, light absorption properties, and reactive oxygen species (ROS) generation. Following aerosol evaporation, solutes become concentrated, accelerating reactions within the aerosol matrix that lead to a 42% reduction in peroxide content and noticeable browning of the SOA. This process occurs most effectively at moderate relative humidity (∼40%), reaching a maximum solute concentration before aerosol solidification. Molecular characterization reveals that evaporating VCP-derived SOA produces highly conjugated nitrogen-containing products from interactions between existing or transformed carbonyl compounds and reduced nitrogen species, likely acting as chromophores responsible for the observed brownish coloration. Additionally, the reactivity of VCP-derived SOA was elucidated through heterogeneous oxidation of sulfur dioxide (SO2), which revealed enhanced photosensitized sulfate production upon drying. Direct measurements of ROS, including singlet oxygen (1O2), superoxide (O2•-), and hydroxyl radicals (•OH), showed higher abundances in dried versus undried SOA samples under light exposure. Our findings underscore that drying significantly alters the physicochemical properties of VCP-derived SOA, impacting their roles in atmospheric chemistry and radiative balance.

MATHEMATICAL MODELING AND EVALUATION OF THERMODYNAMIC PERFECTION OF A CHEMICAL REACTOR

The development of a formalized mathematical model for quantitative and qualitative assessment of the thermodynamic perfection of a gas chemical reactor is described in the article. The reactor was considered as an energy technology system, that is, in the unity of the transformation of matter and energy. Mathematical modeling and evaluation of the thermodynamic perfection of a chemical reactor is generalized to a class of known chemically active gas systems characteristic of ammonia synthesis, sulfur dioxide oxidation, methanol synthesis, nitric oxide oxidation, etc. The equilibrium degree of transformation of a substance and exergy are taken as the determining parameters for modeling and evaluating the thermodynamic perfection of a chemical reactor. These parameters are functions of temperature and reflect the opposing tendencies of the process when it changes, the evaluation of which allows us to quantify the finding of the maximum exergy in the coordinates (E-T) when justifying the optimal temperatures of the process. The model was tested on a specific example of a sulfur dioxide oxidation reactor in the production of sulfuric acid. The public Octave programming environment was used for computer modeling. The developed mathematical model is recommended to be used in the operational preparation and optimization of the initial data for the design of gas reactors. The mathematical model can be supplemented with a mathematical model developed by the authors earlier for quantifying the current profile of the degrees of transformation of the target component of a chemically active reactive gas mixture in the course of its movement in a polytropic tubular reactor of the "pipe in a pipe" type. After testing and setting up the model in practice, it can be used in an automated control system for chemical reactors, including when creating adaptive control systems. For citation: Andreev A.S., Aksenchik K.V. Mathematical modeling and evaluation of thermodynamic perfection of a chemical reactor. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 114-120. DOI: 10.6060/ivkkt.20246705.6964.

Insight studies on the deactivation of sulfuric acid regeneration catalyst

The SAR unit is used for regenerating spent sulfuric acid for alkylation reactions. In the SAR unit, the converter employs a potassium and vanadium-based catalyst for conversion of SO2 to SO3. The multiple bed fixed bed reactor is there to ensure that almost entire amount of SO2 is converted to SO3. On observing the generation of large amounts of fines in the reactor catalyst, the spent catalyst and fines are collected for insight studies. The current study enlightens the possible causes of catalyst deactivation and fines generation. Structural changes in potassium/vanadium based catalyst during the oxidation of sulfur dioxide identified as the major cause of catalyst deactivation. Such structural changes and their impact on catalyst property were determined using various physico-chemical characterization methods like crushing strength, Loss on drying (LOD), XRF, XRD, FTIR and XPS analysis. LOD analysis shows the higher moisture and volatile content in spent and fines compared to fresh catalyst. High moisture content in spent catalyst decreases hardness of catalyst resulting in leaching of vanadium salt and carrier degradation due to thermal cycling. Chemical analysis data found to show the active vanadium content in fines is higher compared to spent which indicates vanadium has leached out from fresh catalyst and is deposited on fines. These observations are further correlated with XRD and XPS results. XPS analysis shows the relative distribution of V4+ and V5+ species on the catalyst surface are altered and found very low concentration of V4+ sites on spent catalyst. The XRD analysis demonstrates the leaching of the active component, potassium vanadyl sulfate K(VO2) (SO4)·3H2O, which then accumulated in the fines fraction. FT-IR and XRD results further shows increase in sulfate accumulation on spent catalyst surface along with phase changes. FTIR analysis of simulated spent catalyst are well correlated with these findings.

Significantly Accelerated Photosensitized Formation of Atmospheric Sulfate at the Air-Water Interface of Microdroplets.

The multiphase oxidation of sulfur dioxide (SO2) to form sulfate is a complex and important process in the atmosphere. While the conventional photosensitized reaction mainly explored in the bulk medium is reported to be one of the drivers to trigger atmospheric sulfate production, how this scheme functionalizes at the air-water interface (AWI) of aerosol remains an open question. Herein, employing an advanced size-controllable microdroplet-printing device, surface-enhanced Raman scattering (SERS) analysis, nanosecond transient adsorption spectrometer, and molecular level theoretical calculations, we revealed the previously overlooked interfacial role in photosensitized oxidation of SO2 in humic-like substance (HULIS) aerosol, where a 3-4 orders of magnitude increase in sulfate formation rate was speculated in cloud and aerosol relevant-sized particles relative to the conventional bulk-phase medium. The rapid formation of a battery of reactive oxygen species (ROS) comes from the accelerated electron transfer process at the AWI, where the excited triplet state of HULIS (3HULIS*) of the incomplete solvent cage can readily capture electrons from HSO3- in a way that is more efficient than that in the bulk medium fully blocked by water molecules. This phenomenon could be explained by the significantly reduced desolvation energy barrier required for reagents residing in the AWI region with an open solvent shell.

Quantitative analysis of sulfate formation from crop burning in Northeast China: Unveiling the primary processes and transboundary transport to South Korea

The substantial amount of pollutants produced by crop burning leads to particulate matter (PM2.5) formation through chemical reactions in the atmosphere. In this study, we quantitatively examined the characteristics of PM2.5 component concentration changes and the production mechanism of sulfate (SO42−) due to crop burning in China, during a period of high PM2.5 concentrations in South Korea. Crop burning emissions were obtained from the Fire INventory from NCAR (FINN), and simulations were conducted using the Community Multi-scale Air Quality (CMAQ) model. The concentrations of PM2.5, nitrate, ammonium, organic carbon, and elemental carbon caused by crop burning were the highest in Northeast China, while the SO42− concentration was higher in the Shandong Peninsula and the Yellow Sea. SO42− was mainly produced through the oxidation reaction by hydrogen peroxide (H2O2) (H2O2 + S(IV) = S(VI) + H2O) (1.44 μg/m3, 80.49%). H2O2 that contributed to SO42− production was primarily produced through the self-reaction of hydroperoxy radical (HO2). Moreover, HO2, which contributed to the production of H2O2, was mainly formed through the decomposition of peroxynitric acid (PNA), which is produced by nitric oxide (NOx) emissions from crop burning. SO42− in the Yellow Sea was reported to be predominantly produced by the oxidation of sulfur dioxide (SO2) by hydroxyl radical (OH) (OH + SO2 = SULF + HO2); however, our study suggests that the PNA formed by NOx emissions from crop burning could contribute to an increase in H2O2, which subsequently promotes SO42− production. The produced SO42− was then transported across the Yellow Sea, impacting the elevated PM2.5 concentrations in Jeju Island, a suburban area of South Korea. These findings demonstrate that the mechanisms of SO42− production by crop burning emissions differ from those of anthropogenic emissions.

Assessing the sensitivity of aerosol mass budget and effective radiative forcing to horizontal grid spacing in E3SMv1 using a regional refinement approach

Abstract. Atmospheric aerosols have important impacts on air quality and the Earth–atmospheric energy balance. However, as computing power is limited, Earth system models generally use coarse spatial grids and parameterize finer-scale atmospheric processes. These parameterizations and the simulation of atmospheric aerosols are often sensitive to model horizontal resolutions. Understanding the sensitivities is necessary for the development of Earth system models at higher resolutions with the deployment of more powerful supercomputers. Using the Energy Exascale Earth System Model (E3SM) version 1, this study investigates the impact of horizontal grid spacing on the simulated aerosol mass budget, aerosol–cloud interactions, and the effective radiative forcing of anthropogenic aerosols (ERFaer) over the contiguous United States. We examine the resolution sensitivity by comparing the nudged simulation results for 2016 from the low-resolution model (LR) and the regional refinement model (RRM). As expected, the simulated emissions of natural dust, sea salt, and marine organic matter are substantially higher in the RRM than in the LR. In addition, RRM simulates stronger aqueous-phase production of sulfate through the enhanced oxidation of sulfur dioxide by hydrogen peroxide due to increased cloud liquid water content. In contrast, the gas-phase chemical production of sulfate is slightly suppressed. The RRM resolves more large-scale precipitation and produces less convective precipitation than the LR, leading to increased (decreased) aerosol wet scavenging by large-scale (convective) precipitation. Regarding aerosol effects on clouds, RRM produces larger temporal variabilities in the large-scale liquid cloud fractions than LR, resulting in increased microphysical cloud processing of aerosols (more interstitial aerosols are converted to cloud-borne aerosols via aerosol activation) in RRM. Water vapor condensation is also enhanced in RRM compared to LR. Consequently, the RRM simulation produces more cloud droplets, a larger cloud droplet radius, a higher liquid water path, and a larger cloud optical depth than the LR simulation. A comparison of the present-day and pre-industrial simulations indicates that, for this contiguous United States domain, the higher-resolution increases ERFaer at the top of the model by about 12 %, which is mainly attributed to the strengthened indirect effect associated with aerosol–cloud interactions.

Important Role of Low Cloud and Fog in Sulfate Aerosol Formation During Winter Haze Over the North China Plain

AbstractSulfate aerosol greatly contributes to wintertime haze pollution in emission‐intensive regions like the North China Plain (NCP) in China. Fast sulfate increase and accumulation are usually recorded during winter haze; however, the multiphase oxidation of sulfur dioxide (SO2) and the physical processes affecting near‐surface sulfate are not fully understood. By combining in situ observations and numerical simulations, we found that high sulfur oxidation ratios (>0.6) under heavily polluted conditions are associated with low clouds and fog over NCP, induced by the moist southerly airflow. Thick low clouds and high SO2 levels in NCP provide a reaction environment for sulfate production. The sulfate production rate in cloud water can reach 0.5–1.3 μg m−3 h−1. The results demonstrate that the vertical mixing of sulfate generated within the cloud water to the surface plays a significant role in rapid sulfate production, highlighting the importance of understanding cloud‐water processes in haze pollution.

On the Mechanism of Sulfur Dioxide Oxidation in Cloud Drops

On the Mechanism of Sulfur Dioxide Oxidation in Cloud Drops

On the Mechanism of Sulfur Dioxide Oxidation in Cloud Droplets

Data from field experiments on the dynamics of SO2 oxidation in cloud droplets are presented. The rapid oxidation of SO2 by molecular oxygen observed in experiments is attributed here to the catalytic action of a pair of manganese and iron ions in droplets. Their inhomogeneous effect by the drop-size distribution, attributed in experiments only to the leaching of ions of these metals from coarse particles of mineral dust is also due to the transition of the oxidation reaction into a branched mode. The results obtained indicate that the branched regime of catalytic oxidation of SO2 detected in cloud droplets should be considered as a new and significant source of sulfates in the atmosphere. This process must be taken into account when considering both the budget of sulfates in the global atmosphere and their impact on the climate.

Oxalate-Promoted SO2 Uptake and Oxidation on Iron Minerals: Implications for Secondary Sulfate Aerosol Formation.

Mineral dust serves as a significant source of sulfate aerosols by mediating heterogeneous sulfur dioxide (SO2) oxidation in the atmosphere. Given that a considerable proportion of small organic acids are deposited onto mineral dust via long-range transportation, understanding their impact on atmospheric SO2 transformation and sulfate formation is of great importance. This study investigates the effect of oxalate on heterogeneous SO2 uptake and oxidation phenomenon by in situ FTIR, theoretical calculation, and continuous stream experiments, exploiting hematite (Fe2O3) as an environmental indicator. The results highlight the critical role of naturally deposited oxalate in mononuclear monodentate coordinating surface Fe atoms of Fe2O3 that enhances the activation of O2 for oxidizing SO2 into sulfate. Meanwhile, oxalate increases the hygroscopicity of Fe2O3, facilitating H2O dissociation into reactive hydroxyl groups and further augmenting the SO2 uptake capacity of Fe2O3. More importantly, other conventional iron minerals, such as goethite and magnetite, as well as authentic iron-containing mineral dust, exhibit similar oxalate-promoted sulfate accumulation behaviors. Our findings suggest that oxalate-assisted SO2 oxidation on iron minerals is one of the important contributors to secondary sulfate aerosols, especially during the nighttime with high relative humidity.

Interactive Stratospheric Aerosol Microphysics‐Chemistry Simulations of the 1991 Pinatubo Volcanic Aerosols With Newly Coupled Sectional Aerosol and Stratosphere‐Troposphere Chemistry Modules in the NASA GEOS Chemistry‐Climate Model (CCM)

AbstractWe have coupled the GEOS‐Chem tropospheric‐stratospheric chemistry mechanism and the Community Aerosol and Radiation Model for Atmospheres (CARMA), a sectional aerosol microphysics module, within the NASA Goddard Earth Observing System Chemistry‐Climate Model (GEOS CCM) in order to simulate the interactions between stratospheric chemistry and aerosol microphysics. We use observations of the 1991 Mount Pinatubo volcanic cloud to evaluate this new version of the GEOS CCM. The GEOS‐Chem chemistry module is used to simulate the oxidation of sulfur dioxide (SO2) more realistically than assuming hydroxyl radical (OH) fields are constant, as OH concentrations in the plume decrease dramatically in the weeks following the eruption. CARMA simulates sulfate aerosols with dynamic microphysical and optical properties. The CARMA‐calculated aerosol surface area is coupled to the chemistry module from GEOS‐Chem for the calculation of heterogeneous chemistry. We use a set of observational and theoretical constraints for Pinatubo to evaluate the performance of this new version of the GEOS CCM. These simulations are specifically compared with satellite and in‐situ observations and provide insights into the connections between the gas‐phase chemistry and the aerosol microphysics of the early plume and how they impact the climatic and chemical changes following a large volcanic eruption. A second, smaller eruption is also included in these simulations, the 15 August 1991, eruption of Cerro Hudson in Chile, which we find essential in explaining the aerosol optical depth in the Southern Hemisphere in 1991.

Acid Rain Formation and Its Direct Impacts on Plants: Wheat and Rice

Acid rain is a serious environmental problem that occurs in many places around the world. Acid deposition can form as a result of the oxidation of sulfur dioxide and nitrogen oxide gases that are released into the atmosphere. These gases (SO2, NOx) are the primary causes of acid rain, and physically and chemically react with water, oxygen, and other chemicals to form other acidic compounds such as sulfuric acid (H2SO4) and nitric acid (HNO3). Acid rain can form in the presence of ozone and carbon dioxide as well. Sulfuric acid (H2SO4) and nitric acid (HNO3) affect biological systems like plants directly. This paper provides information about acid formation and the direct impacts of acid rain on plants. Through a survey of the literature, we assessed the direct effects of acid rain on leaf chlorophyll, growth, and yield parameters on crops that have the highest economic importance in Afghanistan. (e.g., wheat, rice). For the analysis of the data, linear regression was applied. The results showed that plant parameters (dependent variables) such as leaf length, leaf area, chlorophyll content, leaf dry weight, and weight of 1000 seeds of wheat; leaf area; net-photosynthetic rate; and leaf dry weight of rice can be significantly affected by pH treatments (pH 5.5–2.5) (independent variables). The trends of the analysis determined significant negative effects of acid rain on plant parameters. To reduce the impacts of acid rain on plants, it is necessary to apply adaptation and mitigation strategies.

Sulfur Dioxide Oxidation by Zinc and Zinc Oxide Nitrate/Nitrite Complexes in the Gas Phase: An Interplay between Redox-Active Ligands and Metal.

Different oxidative pathways of sulfur dioxide promoted by ZnO(NO3 )2 - , Zn(NO3 )2 - and Zn(NO2 )(NO3 )- are revealed by a joint investigation by mass spectrometry and theoretical calculations. The reactions are triggered by [Zn2+ -O- ⋅]+ or by the low-valence Zn+ through oxygen ion transfer or electron transfer to SO2 , respectively. The NOx - ligands intervene in the oxidation only when sulfur dioxide is converted to SO3 - or SO2 - , leading to the formation of zinc sulfate and zinc sulfite coordinated to nitrate or nitrite anions. Kinetic analyses show that the reactions are fast and efficient, and theory discloses the elementary steps, namely oxygen ion transfer, oxygen atom transfer and electron transfer, occurring through similar energy landscapes for the three reactive anions.

Sources, sinks, and chemistry of Stabilized Criegee Intermediates in the Indo-Gangetic Plain

Night-time oxidation significantly affects the atmospheric concentration of primary and secondary air pollutants but is poorly constrained over South Asia. Here, using a comprehensively measured and unprecedented set of precursors and sinks of Stabilized Criegee Intermediates (SCI), in the summertime air of the Indo-Gangetic Plain (IGP), we investigate the chemistry, and abundance in detail. This study reports the first summertime levels from the IGP of ethene, propene, 1-butene, cis-2-butene, trans-2-butene, 1-pentene, cis-2-pentene, trans-2-pentene, and 1-hexene and their possible roles in SCI chemistry. Ethene, propene, and 1-butene were the highest ambient alkenes in both the summer and winter seasons. Applying chemical steady-state to the measured precursors, the average calculated SCI concentrations were 4.4 (±3.6) × 103 molecules cm−3, with Z-CH3CHOO (55 %) as the major SCI. Z-RCHOO (35 %) and α-pinene derived PINOO (34 %) were identified as the largest contributors to SCI with a 7.8 × 105 molecules cm−3 s−1 production rate. The peak SCI occurred during the evenings. For all SCI species, the loss was dominated (>50 %) by unimolecular decomposition or reactions with water vapor or water vapor dimer. Pollution events influenced by crop burning resulted in significantly elevated SCI production (2.1 times higher relative to non-polluted periods) reaching as high as (7.4 ± 2.5) × 105 molecules cm−3 s−1. Among individual SCI species, Z-CH3CHOO was highest in all the plume events measured accounting for at least ~41 %. Among alkenes, trans-2-butene was the highest contributor to P(SCI) in plume events ranging from 22 to 32 %. SCIs dominated the night-time oxidation of sulfur dioxide with rates as high as 1.4 (±1.1) × 104 molecules cm−3 s−1 at midnight, suggesting that this oxidation pathway could be a significant source of fine mode sulfate aerosols over the Indo-Gangetic Plain, especially during summertime biomass burning pollution episodes.

Formation and properties of block vanadium SiO<sub>2</sub> nanomaterial catalyst for SO<sub>2</sub> oxidation

A method for producing a block vanadium catalyst for the oxidation of sulfur dioxide has been studied, which includes the stage of preparing a honeycomb structure framework based on silica raw materials in the form of white soot, followed by applying a substrate in the form of amorphous silicon dioxide and an active component to the surface of the channels. Data on the structural and mechanical properties of the honeycomb catalyst paste have been obtained. A mode of heat treatment of molded products with the production of mechanically strong blocks as carriers of the vanadium catalyst is proposed. Information about the performance of a block vanadium catalyst in comparison with an industrial catalyst of a granular form is given. Ill. 4. Ref. 14. Tab. 1.

Sulfate formation via aerosol-phase SO2 oxidation by model biomass burning photosensitizers: 3,4-dimethoxybenzaldehyde, vanillin and syringaldehyde using single-particle mixing-state analysis

Abstract. Atmospheric oxidation of sulfur dioxide (SO2) to sulfate has been widely investigated by means of gas-phase and in-cloud chemistry studies. Recent field measurements have shown significant sulfate formation in cloud-free environments with high aerosol loadings. As an important fraction of biomass burning aerosol components, particulate phenolic and non-phenolic aromatic carbonyls may initiate photosensitized multiphase oxidation of SO2 in aerosols, of which our knowledge however is still in its nascent stage. In this study, on the basis of single-particle aerosol mass spectrometry (SPAMS) measurements, we find evident sulfate formation in the biomass-burning-derived photosensitizer particles under UV and SO2 exposure, attributable to photosensitized oxidation of S(IV), while almost no sulfate was observed under dark conditions. The efficiency of sulfate production by photosensitizer particles under UV irradiation, represented by the number percentage of sulfate-containing particles (99 %–43 %) and the relative peak area (RPA) of sulfate (0.67–0.12) in single-particle spectra, in descending order, were 3,4-dimethoxybenzaldehyde (DMB), vanillin (VL) and syringaldehyde (SyrAld). Internal mixtures of VL and potassium nitrate (KNO3) gave a slightly lower number percentage and RPA of sulfate than VL particles alone. In externally mixed VL and KNO3 particles, sulfate was predominantly formed on the former, confirming that sulfate formation via photosensitization prevails over that via nitrate photolysis. Our results suggest that photosensitized oxidation of S(IV) could make an important contribution to aerosol sulfate formation, especially in areas influenced by biomass burning.

Ionic Strength Enhances the Multiphase Oxidation Rate of Sulfur Dioxide by Ozone in Aqueous Aerosols: Implications for Sulfate Production in the Marine Atmosphere.

Multiphase oxidation of sulfur dioxide (SO2) by ozone (O3) in alkaline sea salt aerosols is an important source of sulfate aerosols in the marine atmosphere. However, a recently reported low pH of fresh supermicron sea spray aerosols (mainly sea salt) would argue against the importance of this mechanism. Here, we investigated the impact of ionic strength on the kinetics of multiphase oxidation of SO2 by O3 in proxies of aqueous acidified sea salt aerosols with buffered pH of ∼4.0 via well-controlled flow tube experiments. We find that the sulfate formation rate for the O3 oxidation pathway proceeds 7.9 to 233 times faster under high ionic strength conditions of 2-14 mol kg-1 compared to the dilute bulk solutions. The ionic strength effect is likely to sustain the importance of multiphase oxidation of SO2 by O3 in sea salt aerosols in the marine atmosphere. Our results indicate that atmospheric models should consider the ionic strength effects on the multiphase oxidation of SO2 by O3 in sea salt aerosols to improve the predictions of the sulfate formation rate and the sulfate aerosol budget in the marine atmosphere.

Simultaneous oxidation and absorption of nitric oxide and sulfur dioxide by peroxymonosulfate activated by bimetallic metal-organic frameworks

SO2 and NO from coal combustion are the main precursors of acid rain, regional haze, and photochemical smog. Advanced oxidation strategies can be used to simultaneously remove SO2 and NO from flue gas under a low temperature. Two metal-organic frameworks (MOFs), FeBDC and CuFeBDC, were synthesized and used to activate peroxymonosulfate (PMS) for the oxidation and absorption of flue pollutants. The characterization results revealed that MOFs contained the redox pairs Fe(II)/Cu(I) and Fe(III)/Cu(II). Fe(II)/Cu(I) initiated firstly the PMS activation. Then, the Fe(II-III-II) and Cu(I-II-I) redox cycles continuously activated PMS and generated reactive species. MOFs-PMS removed 76.6 % and 86.5 % of NO in the presence of FeBDC and CuFeBDC catalysts, respectively. 100 % of SO2 was removed. CuFeBDC exhibited the efficient catalytic properties for the removal of NO and SO2 in PMS solution, and could be recycled and regenerated. After five cycles, the removal efficiencies of NO and SO2 were 71.2 % and 100 %, respectively, and NO and SO2 emissions in the outlet were lower than the emission limit when using CuFeBDC-PMS. During the oxidation and absorption process, NO and SO2 were first oxidized to NO2- and SO32- as intermediates, then formed the final products of NO3- and SO42-. Radical scavenging experiments and electron paramagnetic resonance measurements revealed that both radical (SO4-•, •OH) and non-radical pathways (1O2) contributed to the efficient oxidation of NO/ SO2. 1O2 was the predominant reactive oxygen species for the removal of NO, while SO4-• and •OH were responsible for the removal of SO2.